Reagentless Amperometric Biosensor For Nadh Detection

Abstract

A sensitive and selective amperometric biosensor, based on NADH-oxidase (NADOx) working in tandem with horseradish peroxidase (HRP), which is electrically connected to graphite electrode via Os-redox polymer (RP), was developed. Two designs were considered for the biosensor optimization: (i) the first one, [G/HRP-NADOx], exploited the direct electron transfer between HRP and the graphite electrode (G); (ii) the second one, [G/RP-HR-P-NADOx], used R-P as mediator. In both cases the enzyme matrix was cross-linked using poly(ethylenglycol) diglycidyl ether. The biosensors sensitivities, estimated as the slopes of linear ranges from the calibration curves, recorded in a single line flow injection setup, showed that G/RP-HRP-NADOx electrode (1.62 +/- 0.05 mA M-1) presents a higher efficiency than G/HRP-NADOx electrode (0.30 +/- 0.03 mA M-1)